A voltage controlled oscillator (VCO) is one element of a phase-locked loop (PLL) circuit that is used in many applications in integrated circuits, among other. In an integrated circuit, a PLL circuit can be used, e.g., to generate an internal clock signal of a certain frequency from, e.g., a lower frequency reference signal. Because of process variations in an integrated circuit, a VCO in an integrated circuit may require several frequency bands from which its operating frequency is selected. Consequently, an LC (inductor/capacitor) tank circuit for the VCO may be provided that has a fixed set of frequency bands from which to choose at the initial start up of the PLL circuit (e.g., during the power-up sequence). However, when the VCO is operating, power supply voltage variations and temperature variations over time may effect the VCO frequency. For example, if the capacitance of the LC tank circuit changes with temperature the PLL circuit has no mechanism for automatically adjusting its frequency band during operation and, consequently, the PLL circuit may lose its lock status and operate inefficiently, which is not acceptable in many applications.